In the manufacture of semiconductor devices, photolithography is used to transfer the image of a pattern like a circuit pattern to a substrate in a wafer. Typically, a photolithography process entails a coating process of coating the substrate with photoresist, an exposure process of aligning the substrate with a mask bearing the pattern and directing light such as ultraviolet light through or reflected by the mask and onto the layer of photoresist, and a developing process of developing the exposed layer of photoresist to remove select (exposed or non-exposed) portions of the photoresist,thereby patterning the layer of photoresist.
The photolithography process may additionally include a primer (e.g., hexamethyldisilazane (HMDS)) coating process and one or more baking processes. The primer coating process is performed to improve the adhesion of the photoresist to the substrate. A baking process may be performed to remove moisture or an organic solvent from the substrate before the substrate is coated with the photoresist. Also, a baking process may be performed after the substrate has been coated with the photoresist to remove solvent from the photoresist.